Right associated with left ventricular infarction was identified by gross examination at necropsy in 33 (14 percent) of 236 patients with transmural myocardial infarction. Right ventricular infarction occurred exclusively as a complication of posterior left ventricular infarction. Of 97 patients with isolated anterior wall infarction of the left ventricle, none had associated right ventricular infarction, 33 (24 percent) has associated right ventricular infarction.